The first time I road I put together a bike with an Italian BB I tightened the BB as I would normally tighten an English BB. I rode about 200 miles and fixed cup came un-fixed half way through a 40mi ride (it was stop, tighten finger tight, ride 2-3 miles stop tighten finger tight, etc..). When I got home I removed and re-greased the the bottom bracket and tightened the fixed cup, best effort with a 24" breaker bar (no loc-tite). I've got about 1000 miles on the BB and it's stuck solid (that's a good thing!). I don't know why your French BB came loose if you couldn't loosen it before, but as eschlwc said